There is increasing interest in operating radio equipment in a single vehicle on different frequency bands. However, many automobile owners are reluctant to mount multiple antennas on their vehicles because of the bristly appearance that results and because of the need to make multiple feed cable pass through holes in the vehicle exterior.
It is also often considered desirable to retract a radio antenna into the body of a vehicle such as a passenger automobile. There are numerous reasons, but in the case of such an automobile they include leaving the car lines clean when the radio is not in use and presenting fewer visible clues of the existence of or nature of radio equipment within the vehicle. The use of electrically powered mechanisms, coupled through a flexible rod, or cable element, makes it convenient to extend or retract telescopic antenna elements at will from inside the vehicle. A U.S. Pat. No. 4,323,902 to J. L. Hussey et al. is an example of such a powered telescopic antenna.
The need for multiband operation has led to systems in which an additional band, besides e.g., the AM/FM commercial broadcast reception band, capability has been added. For example in the U.S. Pat. No. 4,095,229 to J. O. Elliott there is shown a single antenna with loading coil which is coupled, through a single feed line and a splitter, to separate AM/FM and CB radios. Also, a U.S. Pat. No. 4,325,069 to J. F. Hills shows a telescopic antenna modified by adding to the next-to-the-top segment a loading coil module which produces an effective length suitable for transmission and reception in the citizens' band while still providing acceptable reception in the mentioned commercial broadcast band.
A C. W. Miley U.S. Pat. No. 3,541,557 shows a multiband, tunable, notch antenna that has multiple horizontal blade pairs which are separate tunable. A single feed line is used for all pairs.
A bent-arm multiband antenna of a D. O. Morgan U.S. Pat. No. 3,229,298 has conductors thereof folded back on themselves so it operates at, e.g., half-wave and quarter-wave lengths without the use of loading coils or tuning stubs.
In a K. L. Leidy U.S. Pat. No. 3,139,620, a coaxial, multiband antenna has all elements for the different bands fed from the same line. The two highest frequency bands are half-wave dipoles with quarter-wave skirts at each end to define their respective operating lengths. A central high-band section includes a high-band dipole and its associated skirt-type quarter-wave stubs; and a lower-band section includes a lower-band dipole (comprising the high-band section stubs) and quarter-wave stubs for the lower-band dipole. The third and lowest band is a whip mounted on top of the upper end of the high bands dipoles combination.